For example, in the related art, a pulverized coal burning boiler includes a furnace which has a hollow shape and is installed in a vertical direction, and a plurality of combustion burners are disposed on a wall of the furnace along a circumferential direction and are arranged in a plurality of stages in an upward-downward direction. A gaseous mixture of pulverized coal (fuel) which is crushed coal and transport air (primary air) is supplied to the combustion burner, high-temperature secondary air is supplied to the combustion burner, flames are generated by blowing the gaseous mixture and the secondary gas into the furnace, and combustion gas can be generated in the furnace. In addition, a flue is connected to the upper portion of the furnace, a superheater, a reheater, an economizer, or the like for collecting heat of flue gas is provided in the flue, water is heated by exhaust gas generated by combustion in the furnace, and steam can be generated. In addition, a flue gas passage is connected to the flue, a denitration device, an electric dust collector, a desulfurization device, or the like is provided in the flue gas passage, and a chimney is provided on a downstream end portion of the flue gas passage.
For example, as the boiler, there are boilers which are disclosed in PTLs below.